test: reduce flakiness of system test: Order of flow definition updates does not matter

[reubenmiller]

Proposed changes

Improve the "Order of flow definition updates does not matter" system test to reduce the flakiness.

flake-finder report

Before

$ invoke flake-finder --suite "tedge_flows" --iterations 20 --clean
------------------------------
Overall: FAILED
Results: 20 iterations, 14 passed, 6 failed
Elapsed time: 0:23:02.111119
Failed iterations: [1, 3, 5, 9, 10, 16]

After

$ invoke flake-finder --suite "tedge_flows" --iterations 20 --clean
------------------------------
Overall: PASSED
Results: 20 iterations, 20 passed, 0 failed
Elapsed time: 0:23:23.797479

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (general improvements like code refactoring that doesn't explicitly fix a bug or add any new functionality)
• Documentation Update (if none of the other choices apply)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Paste Link to the issue

The following runs observed an error.

• https://github.com/thin-edge/thin-edge.io/actions/runs/22460183209/job/65053098379
• https://github.com/thin-edge/thin-edge.io/actions/runs/22452977186/job/65027826391

Checklist

• I have read the CONTRIBUTING doc
• I have signed the CLA (in all commits with git commit -s. You can activate automatic signing by running just prepare-dev once)
• I ran just format as mentioned in CODING_GUIDELINES
• I used just check as mentioned in CODING_GUIDELINES
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

Further comments

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
843	0	3	843	100	2h41m28.124208999s

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[didier-wenzek]

Approved